Liposome Formulation of Fluticasone Furoate and Method of Preparation

ABSTRACT

The present invention is directed to a liposomal formulation having a lipid ingredient encapsulating fluticasone furoate, and a method for preparing the liposomal formulation. The liposome formulation comprises a lipid and a sterol. The method of preparing the liposomes comprises the steps of (1) mixing fluticasone furoate with lipid ingredients comprising a lipid and a sterol, (2) injecting the mixture into normal saline solution, and (3) ultrafiltering and concentrating the resulting solution. This preparation method can produce a liposome formulation having desirable properties and compositions, for example, the ratio of the lipid ingredient, the drug to lipid ratio, and the pH value, which is suitable for nebulization inhalation.

PRIORITY STATEMENT

This application claims the benefit of U.S. Provisional PatentApplication No. 62/892,567, filed on Aug. 28, 2019, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Fluticasone furoate, chemically known as (6α, 11β, 16α,17α)-6,9-difluoro-17-{[(fluoro-methyl)thio]carbonyl}-11-hydroxy-16-methyl-3-oxoandrosta-1,4-dien-17-yl2-furancarboxylate, has the following structure:

Fluticasone furoate has been described in U.S. Pat. Nos. 8,148,353,7,101,866, and 6,777,400. Fluticasone can be used for the treatment ofasthma, chronic obstructive pulmonary disease (COPD), and allergicrhinitis. Asthma is a major cause of chronic morbidity and mortality. Itis estimated that about 250,000 annual deaths are attributed to thedisease. Asthma is a chronic inflammatory disorder of the airwaysassociated with airway hyper-responsiveness that leads to recurrentepisodes of wheezing, breathlessness, or coughing. Conventional drypowder inhalation of fluticasone furoate shows some disadvantages inlung dispositions and efficiency for treatment of asthma and chronicobstructive pulmonary disease (COPD). Therefore, there is a need todevelop formulations for fluticasone furoate that improve lungdisposition and efficiency.

Liposomes are microscopic closed vesicles which have an internal phaseenclosed by one or more lipid bilayers. Liposomes can entrap the activeagent fluticasone furoate in the liposome with high efficiency andsecure stable retention of fluticasone furoate by the liposomeconstituents so that the fluticasone furoate can be delivered to atarget tissue. Liposomes can improve protection of the encapsulateddrug, increase drug stability, change the in vivo distribution behaviorof the drug, and carry the drug to a diseased region by passive oractive targeting, as well as improve drug efficacy and reduce drugtoxicity.

The present invention relates to liposomes encapsulating fluticasonefuroate and to a liposomal formulation having high size uniformity,higher drug-loading capacity, as well as high encapsulation efficiency.The liposomal formulations disclosed in the present invention areespecially suited for nebulization inhalation and provide improved lungdeposition.

In addition, liposomal formulations are advantageous compared withconventional dry powder inhalation. For example, administration by meansof dry powder inhalation is more difficult, particularly for childrenand elderly patients. Also, dry powder inhalation may cause side effectsin the lung. The liposomal formulations of the present invention areparticularly suited for administering fluticasone furoate bynebulization inhalation, especially for treating asthma and chronicobstructive pulmonary disease.

SUMMARY OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

The present invention relates to liposomes encapsulating fluticasonefuroate and methods for its preparation. One aspect of the inventionprovides liposomes having a high uniformity, which results in minimizingside effects, high drug-loading capacity, high encapsulation efficiency,and good stability, and are suitable for preparing a liposomeformulation.

The liposome formulation is characterized by liposomes having desirablecomposition and physical characteristics. The liposome formulation ofthe present invention comprises lipid ingredients encapsulatingfluticasone furoate.

The liposome formulation of the present invention is composed of one ormore lipid ingredients and fluticasone furoate, having a mass ratio offluticasone furoate to that of the lipid ingredient(s), called the drugto lipid ratio, of about 1:10 to about 1:40 by weight.

The liposomes of the present invention are in the size range of about 30to about 1000 nm, more specifically in the size range of about 100 toabout 500 nm, depending on the type of fluticasone furoate and/or thecarrier used. In one embodiment, the liposomes are in the size range ofabout 150 nm.

Another aspect of the present invention is to provide an efficientmethod for producing the liposomes. Liposomes formulated by this processhave desirable characteristics. The method of preparing the liposomesincludes the steps of (1) mixing fluticasone furoate with lipidingredients comprising a lipid and a sterol, (2) injecting the mixtureinto normal saline solution to form liposome vesicles, and (3)ultrafiltration and concentration of the resulting liposomevesicle-containing solution.

In one embodiment, the formulation is prepared by (1) mixing fluticasonefuroate with lipid ingredients comprising DPPC and cholesterol in amolar ratio of about 1:1, with the mass ratio of fluticasone furoate tolipid in the range of about 1:10 to about 1:40; (2) injecting themixture into normal saline solution to form liposome vesicles; and (3)ultrafiltration and concentration of the resulting liposomevesicle-containing solution.

Yet another aspect of the present invention is a liposome formulationmade in accordance with the preparation steps described above. Theformulation comprises a plurality of liposomes, composed of an amount ofone or more lipid ingredients encapsulating fluticasone furoate. In oneembodiment, the lipid ingredients comprise DPPC and cholesterol, and themass ratio of fluticasone furoate to lipid ingredients is in the rangeof about 1:10 to about 1:40. The formulation is prepared by thefollowing steps: (1) mixing fluticasone furoate with lipid ingredientscomprising a lipid and a sterol, (2) injecting the mixture into normalsaline solution to form liposome vesicles, and (3) ultrafiltration andconcentration of the resulting liposome vesicle-containing solution.

This preparation method can produce a liposome formulation, which hasuseful features, for example, the ratio of the lipid ingredients and thepH value.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the size distribution of fluticasone furoateliposome of sample 1 in example 2.

FIG. 2 is a graph of the size distribution of fluticasone furoateliposome of sample 2 in example 2.

FIG. 3 is a graph of the size distribution of fluticasone furoateliposome of sample 3 in example 2.

FIG. 4 is a graph of the size distribution of fluticasone furoateliposome of sample 4 in example 2.

FIG. 5 is a graph of the size distribution of fluticasone furoateliposome of sample 5 in example 2.

FIG. 6 is a graph of particle size distribution of droplets formed usinga compressed air nebulizer.

FIG. 7 is a graph of particle size distribution of droplets formed usingan ultrasonic vibrating mesh nebulizer.

The use of identical or similar reference numerals in different figuresdenotes identical or similar features.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of describing the invention, reference now will be made indetail to embodiments and/or methods of the invention, one or moreexamples of which are illustrated in or with the drawings. Each exampleis provided by way of explanation of the invention, not limitation ofthe invention. In fact, it will be apparent to those skilled in the artthat various modifications and variations can be made in the presentinvention without departing from the scope or spirit of the invention.For instance, features or steps illustrated or described as part of oneembodiment can be used with another embodiment or steps to yield a stillfurther embodiments or methods. Thus, it is intended that the presentinvention covers such modifications and variations as come within thescope of the appended claims and their equivalents.

The present invention relates to a liposomal formulation and a methodfor preparing the liposomal formulation. The formulation comprises aplurality of liposomes encapsulating fluticasone furoate. The physicalcharacteristics of each liposome facilitates stability and effectivenessof the liposomal formulation. The formulation is characterized byliposomes which are substantially uniform in size and shape. Inaddition, the invention provides an efficient method for preparing theliposome formulation, which can meet the needs of large-scalepreparation.

As used herein, the term “liposome” refers to microscopic closedvesicles having an internal phase enclosed by lipid bilayer. In thepresent invention, liposome includes small single-membrane liposomes,large single-membrane liposomes, still larger single-membrane liposomes,multilayer liposomes having multiple concentric membranes, liposomeshaving multiple membranes that are not concentric, but irregular, etc.

The term “liposome internal phase” refers to an aqueous region enclosedin the lipid bilayer of the liposome, and is used with the same meaningas “internal water phase” and “liposome internal water phase.”

The present invention relates to a liposome formulation. Differentliposome ingredients may be used to form the liposome of the invention.Preferably, the lipid ingredient is a non-toxic biocompatible lipid, forexample, lipids prepared from phosphatidyl-choline, phosphoglycerol,and/or cholesterol, in an embodiment, the lipid ingredient may comprisedipalmitoylphosphatidylcholine (DPPC), diastearoylphosphatidylcholine(DSPC), diastearoylphosphatidylglycerol (DSPG) and, cholesterol, orcombinations thereof. In one embodiment, the lipid ingredient comprisesDPPC and cholesterol, which may be present in a molar ratio of about1:1.

As used herein, the term “lipid ingredients” refers to a sterol and alipid. For example, cholesterol and diastearoylphosphatidylcholine(DSPC), cholesterol and dipalmitoylphosphatidylcholine (DPPC), etc. Inan embodiment the lipid and sterol may be present in a molar ratio ofabout 1:1, such as from about 0.6:1 to about 1.4:1, more particularlysuch as from about 0.8:1 to about 1.2:1 (lipid:sterol).

The liposome formulation is characterized by liposomes having adesirable composition and physical characteristics, The liposome of thepresent invention comprises lipid ingredients encapsulating fluticasonefuroate. According to the invention, the lipid is selected from thegroup consisting of phosphatidylcholine (PC), phosphatidic acid (PA),phosphatidylethanolamine (PE), phosphatidylglycerol (PG),phosphatidylserine (PS), phosphatidylinositol (PI), dimyristoylphosphatidyl choline (DMPC), distearoylphosphatidyl choline (DSPC),dipalmitoyl phosphatidyl choline (DPPC), dimyristoyl phosphatidylglycerol (DMPG), distearoylphosphatidyl glycerol (DSPG), dioleoylphosphatidyl glycerol (DOPG), dipalmitoylphosphatidyl glycerol (DPPG),dimyristoyl phosphatidyl serine (DRIPS), distearoyl phosphatidyl serine(DSPS), dioleoyl phosphatidyl serine (DOLS), dipalmitoyl phosphatidylserine (DPPS), dioleoyl phosphatidyl ethanolamine (DOPE),palmitoyloleoylphosphatidylcholine (POPC),palmitoyloleoyl-phosphatidylethanolamine (POPE), dioleoyl-phosphatidylethanolamine 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (DOPE-mal),dipalmitoyl phosphatidyl ethanolamine (DPPE),dimyristoylphosphoethanolamine (DMPE),distearoyl-phosphatidylethanolamine (DSPE),distearoylphosphatidylcholine (DSPC), dioleoylphosphatidylcholine(DOPC), dipalmitoylphosphatidylcholine (DPPC),palmitoyloleoylphosphatidylcholine (POPC), andpalmitoyloleoyl-phosphatidylethanolamine (POPE).

According to the invention, the sterol is at least one kind selectedfrom cholesterol.

The lipid ingredients may comprise a lipid and cholesterol. In anembodiment, the lipid ingredients are selected fromdipalmitoylphosphatidylcholine (DPPC) and cholesterol in the range ofabout 0.6:1 to about 1.4:1 (DPPC:cholesterol) in molar ratios. Inanother embodiment the DPPC and cholesterol may be present in a molarratio of about 1:1, more particularly such as from about 0.8:1 to about1.2:1 (DPPC:cholesterol).

Within the scope of the present invention, the “drug to lipid ratio”refers to the relative amounts of the drug to the lipid ingredients bymass that comprise the liposome and/or formulation. In one embodiment,the liposome has a drug to lipid ratio between about 1:10 and about 1:40by weight. In another embodiment, the liposome has a drug to lipid ratiobetween about 1:10 and about 1:20 by weight.

The pH affects the properties of the liposomal formulation in thesolvent. The pH affects the stability, drug leakage rate from theliposome, and drug encapsulation capability of the liposome formulation.The pH value of the liposomal formulation is from about 4.0 to about7.0. In one embodiment, the liposomal formulation has a pH value in therange of about 5.0 to about 6.0.

According to the invention, the liposome formulation comprises aplurality of liposomes which have the characteristics described aboveand being substantially uniform in size and shape. The liposomes may bein the size range of about 50 to about 1000 nm. In an embodiment, thesize range is about 70 to about 800 nm; more particularly, the sizerange is about 70 to about 500 nm. In an embodiment, the size of theliposome is about 150 nm. In another embodiment, the size of theliposome is about 130 nm.

According to the present invention, the liposome formulation may beformulated using one or more physiologically acceptable carrierscomprising excipients and auxiliaries known in the art.

The liposomal formulation may be administered by any route whicheffectively transports the liposomes to the appropriate site of action.One effective route of administration is by inhalation. Other suitableroutes of administration may include intramuscular, subcutaneous andintraperitoneal.

According to the invention, the liposome formulation may comprise anantioxidant selected from the group consisting of water-solubleantioxidants and oil-soluble antioxidants. Examples of oil-solubleantioxidants include, but are not limited to, alpha-tocopherol,alpha-tocopherol succinate, alpha-tocopherol acetate, and mixturesthereof. Examples of water-soluble antioxidants include, but are notlimited to, ascorbic acid, sodium bisulfite, sodium sulfite, sodiumpyrosulfite, L-cysteine, and mixtures thereof.

The process for making the liposome and liposomal formulation permitsmanipulation of the physical characteristics described above, as well ascontrol of certain process parameters, for example, solvent compositionand solvent ratios and vesicle preparation temperature. The preparationof the liposome formulation comprises the steps of: (1) mixingfluticasone furoate with lipid ingredients comprising a lipid and asterol, (2) injecting the mixture into normal saline solution to formliposome vesicles, and (3) ultrafiltration and concentration of theresulting liposome vesicle-containing solution.

This preparation method has the advantage that the physiological andchemical features of the liposome can be controlled and monitored. Forexample, the drug to lipid ratio may be managed by the selection of thelipid ingredients used to form the liposome or the amount of lipidsadded to the dissolved active agent. Increasing the amount of lipidingredients decreases the drug to lipid ratio, and vice versa.

The first step comprises mixing fluticasone furoate and lipidingredients in a solvent to form a lipid solution. In many cases, thelipid solvent is heated to a temperature in the range of about 40° C. toabout 80° C. to facilitate solubilization of the fluticasone furoate andlipid ingredients.

In a preferred embodiment, the lipid solvent is heated to about 50° C.to facilitate solubilization of the fluticasone furoate and lipidingredients.

The second step comprises injecting the mixture into normal salinesolution to form liposome vesicles. The second step may comprise ahydrophilic solution to form liposome vesicles in addition to, or inplace of, the normal saline described above.

The mixture of fluticasone furoate and lipid ingredients is added orinjected into the normal saline, which may be at about ambienttemperature. The normal saline may be optionally heated during theprocess.

The third step comprises ultrafiltration and concentration. Differenttypes of filtration membranes may be used during the ultrafiltrationprocess. In one embodiment, the ultrafiltration step uses a hollow fibermembrane, where the formulation is pushed through the open hollow coresof the fiber, and the micromolecules are filtered through the outermembrane of the fiber, while the relatively larger liposomes remainwithin the fiber. For a new hollow fiber cartridge, the cartridge istypically filled with 100% alcohol for one hour. In an embodiment, thecartridge may be soaked for over one hour.

Following the ultrafiltration step, the process may further include adialyzing step, wherein the formulation is dialyzed against a volume ofa buffered solution. In one embodiment, the buffer solution is a normalsaline. Other buffer additives are known in the art, including, but notlimited to, sucrose, glycine, sodium chloride, succinate, orcombinations thereof. The buffer solution preferably reflects theenvironment of the final formulation that is external to the liposome.Preferably, the buffer solution is isotonic and non-toxic to cells. Thebuffer solution may be filtered to further reduce contaminants and maybe prepared in advance of the preparation process.

The lipid ingredients may be in the form of a solution containing thedesired starting amount of the lipid ingredient in a volume of one ormore lipid solvents. Any suitable lipid ingredient and lipid solvent maybe used. For example, the lipid ingredients may comprise DPPC andcholesterol in a molar ratio of about 1:1, prior to liposome formation.The resultant liposome formed according to this combination of lipidsmay also have about a 1:1 molar ratio of DPPC and cholesterol.

Examples of lipid solvents include, but are not limited to, ethanol,t-butanol, water, and mixtures thereof. The lipid ingredients aredissolved in the lipid solvent.

The initial concentration of lipid ingredients dissolved in the lipidsolvent, such as ethanol, may be in the range of about 0.33 to about 1.0g/L. The lipid solution may be prepared apart from the manufacturingprocess discussed herein.

The mixture of the fluticasone furoate and the lipid solvent forms thelipid solution, The drug to lipid ratio may be controlled by varying theamount of lipid ingredients and fluticasone furoate. Optionally, mildlyheating the lipid solvent may aid in mixing together the lipidingredients and fluticasone furoate. This mixing process can result inefficient encapsulation of fluticasone furoate into multi-lamellarvesicles.

The weight ratio of lipid to drug increases the stability of theliposome formulation without significantly compromising delivery. Thisprocess permits the drug to lipid ratio to be varied in the range ofabout 1:10 to about 1:40 by weight, preferably in the range of about1:10 to about 1:20. In one embodiment, the liposome formulation may beadded to fluticasone furoate at a ratio of about 15 parts lipidingredients to about 1 part fluticasone furoate. In another embodiment,the liposome formulation may be added to fluticasone furoate solution ata ratio of about 10 parts lipid ingredients to about 1 part fluticasonefuroate.

In accordance with the above description, in an embodiment, theformulation is prepared by (1) mixing fluticasone furoate with lipidingredients comprising DPPC and cholesterol in a molar ratio of about1:1, and a mass ratio of fluticasone furoate to lipid ingredients in therange of about 1:10 to about 1:40; (2) injecting the mixture into normalsaline solution to form liposome vesicles; and (3) ultrafiltration andconcentration of the resulting liposome vesicles-containing solution.

Another aspect of this invention is a liposome formulation made inaccordance with the preparation steps described above, wherein theformulation comprises DPPC and cholesterol in a molar ratio of about1:1, and a mass ratio of fluticasone furoate to lipid ingredients in therange of about 1:10 to about 1:40, which is prepared by the followingsteps: (1) mixing fluticasone furoate with lipid ingredients comprisingDPPC and cholesterol in a molar ratio of about 1:1 and a mass ratio offluticasone furoate to lipid ingredients in the range of about 1:10 toabout 1:40, (2) injecting the mixture into normal saline solution toform liposome vesicles, and (3) ultrafiltration and concentration of theresulting liposome vesicles-containing solution. This preparationproduces a liposome formulation having useful characteristics andfeatures as described above, including a pH value ranging between about4.0 and about 7.0.

The following examples are intended to illustrate and exemplify thevarious aspects of carrying out the present invention and are notintended to limit the invention in any way.

EXAMPLE 1

Preparation of 10 ml liposomal formulation:

-   -   Initial total volume: 100 ml;    -   Ethanol volume: 30%;    -   Lipid ingredients: DPPC, cholesterol;    -   Initial lipid ingredients: 0.3 mg/ml;    -   Initial fluticasone furoate: 0.01 mg/ml;    -   Final volume: 10 ml;

Preparation steps:

-   -   (1) mixing fluticasone furoate with lipid ingredients:        -   19.6 mg of DPPC and 10.4 mg of cholesterol were weighed into            30 ml of ethanol, which was heated to a temperature of            50° C. in a beaker, and mixed until completely dissolved to            provide a lipid solution. Then 1 mg of fluticasone furoate            was added to the lipid solution, and the solution was            stirred until completely dissolved.    -   (2) injecting the mixture into normal saline solution to form        liposome vesicles:

-   The lipid solution containing fluticasone furoate was added to 50 ml    of normal saline and mixed for 20 minutes until dissolved. After    that, the solution was transferred into a 100 ml volumetric flask,    and the flask was made to volume with normal saline.    -   (3) ultrafiltration and concentration:        -   A peristaltic pump was connected to a hollow fiber cartridge            for ultrafiltration and concentration. The sample liposome            formulation was pumped through the cartridge for            ultrafiltration.

EXAMPLE 2

In accordance with the preparation method described above, six differentsamples were prepared with high encapsulation efficiency and differentdrug to lipid ratios. The encapsulation efficiency of six samples wasover 80%, and the encapsulation efficiency of sample 5 was more than90%. The average particle size was in the range of 130 nm-160 nm.

Sample 1: 6.5 mg DPPC and 3.5 mg cholesterol were weighed into 30 ml ofethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution. Then 1 mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was then added to 50 ml of normal saline and stirredfor 20 minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposome formulation was concentrated toa volume of 10 mL.

Sample 2: 9.8 mg DPPC and 5,2 mg cholesterol were weighed into 30 ml ofethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution. Then 1 mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was then added to 50 ml normal saline and stirredfor 20 minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposome formulation was concentrated toa volume of 10 mL.

Sample 3: 13.1 mg DPPC and 6.9 mg cholesterol were weighed into 30 ml ofethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution. Then I mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was then added to 50 ml normal saline and stirredfor 20 minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposome formulation was concentrated toa volume of 10 mL.

Sample 4: 16.4 mg DPPC and 8.6 mg cholesterol were weighed into 30 ml ofethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution, Then 1 mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was added to 50 ml normal saline and stirred for 20minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposome formulation was concentrated toa volume of 10 mL.

Sample 5: 19.6 mg DPPC and 10.4 mg cholesterol were weighed into 30 mlof ethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution. Then 1 mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was then added to 50 ml normal saline and stirredfor 20 minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposorne formulation was concentrated toa volume of 10 mL.

Sample 6: 26.2 mg DPPC and 13.8 mg cholesterol were weighed into 30 mlof ethanol, which was heated to a temperature of 50° C. in a beaker, andmixed until completely dissolved to provide a lipid solution. Then 1 mgof fluticasone furoate was added to the lipid solution, and the solutionwas stirred until completely dissolved. The lipid solution containingfluticasone furoate was then added to 50 ml normal saline and stirredfor 20 minutes until completely dissolved. After that, the solution wastransferred into a 100 ml volumetric flask, and the flask was made tovolume with normal saline. The liposome formulation was concentrated toa volume of 10 mL. The results are shown in table 1 and table 2.

TABLE 1 Sample parameters Sam- Sam- Sam- Sam- Sam- Sam- Parameter ple 1ple 2 ple 3 ple 4 ple 5 ple 6 Drug to lipid ratio 1:10 1:15 1:20 1:251:30 1:40 Total 1.003 1.051 1.013 0.939 1.069 0.95 concentration offluticasone furoate (mg/100 ml) Concentration of 0.164 0.194 0.194 0.1220.107 0.17 free fluticasone furoate (mg/100 ml) Encapsulation 83.6781.58 80.88 86.99 90.01 82.08 efficiency (%)

TABLE 2 Physical and chemical properties of the samples Physical &chemical Sam- Sam- Sam- Sam- Sam- Sam- properties ple 1 ple 2 ple 3 ple4 ple 5 ple 6 Appearance Whitish Whitish Whitish Whitish Whitish Whitishsuspen- suspen- suspen- suspen- suspen- suspen- sion sion sion sion sionsion Average 150.8 146.0 147.6 144.9 130.5 173.1 particle size (nm) pH5.42 5.72 5.36 5.31 5.72 6.22

EXAMPLE 3

Sample 5 was sprayed using an ultrasonic vibrating mesh nebulizer and acompressed air nebulizer. Malvern Spraytec was used to measure theparticle size distribution of the droplets. The particle sizedistribution of the droplets is expressed in terms of D10, D50 and D90.As shown in table 3, the D50 values of the droplets formed with both thecompressed air nebulizer and the ultrasonic vibrating mesh nebulizerwere less than 5 pm, and the D90 values of the droplets formed with boththe compressed air nebulizer and the ultrasonic vibrating mesh nebulizerwere less than 12 μm.

TABLE 3 Particle size distribution from different types of nebulizerSample Number Nebulizer D10 D50 D90 Sample 5 Compressed air 1.694 μm4.828 μm 11.16 μm nebulizer Ultrasonic 2.086 μm 3.945 μm 7.295 μmvibrating mesh nebulizer

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. For example, the present invention isnot limited to the physical arrangements or dimensions illustrated ordescribed. Nor is the present invention limited to any particular designor materials of construction. As such, the breadth and scope of thepresent invention should not be limited to any of the above-describedexemplary embodiments, but should be defined only in accordance with thefollowing claims and their equivalents.

What is claimed is:
 1. A formulation comprising a plurality ofliposomes, wherein the liposomes comprise a lipid ingredient encapsulatefluticasone furoate, the lipid ingredient comprises a lipid and asterol, and the molar ratio of lipid to sterol is from about 0.6:1 toabout 1.4:1.
 2. The formulation according to claim 1, wherein theliposomes have an average size of about 50 to about 1000 nm.
 3. Theformulation according to claim 1, having a pH ranging from about 4.0 toabout 7.0.
 4. The formulation according to claim 1, wherein the lipid isselected from the group consisting of phosphatidylcholine (PC),phosphatidic acid (PA), phosphatidylethanolamine (PE),phosphatidylglycerol (PG), phosphatidylserine (PS), phosphatidylinositol(PI), dimyristoyl phosphatidyl choline (DMPC), distearoylphosphatidylcholine (DSPC), dipalmitoyl phosphatidyl choline (DPPC), dimyristoylphosphatidyl glycerol (DMPG), distearoylphosphatidyl glycerol (DSPG),dioleoyl phosphatidyl glycerol (DOPG), dipalmitoylphosphatidylglycerol(DPPG), dimyristol phosphatidyl serine (DMPS), distearoyl phosphatidylserine (DSPS), dioleoyl phosphatidyl serine (DOPS), dipalmitoylphosphatidyl serine (DPPS), dioleoyl phosphatidyl ethanolamine (DOPE),palmitoyloleoylphosphatidylcholine (POPC),palmitoyloleoyl-phosphatidylethanolamine (POPE),dioleoyl-phosphatidylethanolamine4-(N-maleimidomethyp-cyclohexane-1-carboxylate (DOPE-mal), dipalmitoylphosphatidyl ethanolamine (DPPE), dimyristoylphosphoethanolatnine(DMPE), distearoyl-phosphatidylethanolamine (DSPE),distearoylphosphatidylcholine (DSPC), dioleoylphosphatidylcholine(DOPC), dipalmitoylphosphatidylcholine (DPPC), and combinations thereof.5. The formulation according to claim 1, wherein the sterol comprisescholesterol.
 6. The formulation according to claim 1, wherein the lipidingredient comprises dipalmitoylphosphatidylcholine (DPPC) andcholesterol in a molar ratio of about 0.6:1 to about 1.4.1.
 7. Theformulation according to claim 6, wherein the lipid ingredient comprisesdipalmitoylphosphatidylcholine (DPPC) and cholesterol in a molar ratioof about 1:1.
 8. The formulation according to claim 1, wherein theweight ratio of the fluticasone furoate to the lipid ingredients rangesfrom about 1:10 to about 1:25.
 9. The formulation according to claim 1,wherein the liposomes have a D50 value of less than about 12 μm.
 10. Theformulation according to claim 1, further comprising an antioxidantselected from the group consisting of a water-soluble antioxidant and anoil-soluble antioxidant.
 11. The formulation according to claim 10,wherein the oil-soluble antioxidant is selected from the groupconsisting of alpha-tocopherol, alpha-tocopherol succinate,alpha-tocopherol acetate and mixtures thereof, and the water-solubleantioxidant is selected from the group consisting of ascorbic acid,sodium bisulfite, sodium sulfite, sodium pyrosulfite, L-cysteine, andmixtures thereof.
 12. A method of preparing a formulation having aplurality of liposomes, comprising the steps of: (1) mixing fluticasonefuroate with lipid ingredients in a solvent, wherein the lipidingredients comprise a lipid and a sterol, to provide a first mixture;(2) injecting the first mixture into a normal saline solution to form asecond mixture comprising liposome vesicles; and (3) ultrafiltering andconcentrating the second mixture to provide the formulation.
 13. Themethod according to claim 12, wherein the formulation has a pH rangingfrom about 4.0 to about 7.0.
 14. The method according to claim 12,wherein the lipid and the sterol are in a molar ratio of lipid to sterolthat ranges from about 0.8:1 to about 1.2:1.
 15. The method according toclaim 12, wherein the fluticasone furoate and lipid ingredients are in amass ratio that ranges from about 1:10 to about 1:40.
 16. The method ofclaim 12, wherein the first mixture is heated to a temperature rangingfrom about 40° C. to about 80° C.
 17. The method of claim 12, whereinthe solvent is selected from the group consisting of ethanol, t-butanol,water, and combinations thereof.
 18. The method of claim 12, wherein theultrafiltering uses a hollow fiber membrane.
 19. The method of claim 12,wherein the lipid ingredients comprise dipalmitoylphosphatidylcholine(DPPC) and cholesterol in a molar ratio of about 1:1, and the mass ratioof fluticasone furoate to lipid ingredients ranges from about 1:10 toabout 1:40.